Preheat oven to 350 degrees F. Line the bottom of two 9-inch cake pans with parchment paper. Spray with nonstick cooking spray WITH flour or butter and flour pans.
Whisk eggs, milk, lemon juice, lemon extract, and vanilla extract together in a 3-cup (or more) liquid measuring cup. Set aside.
Add blueberries to a medium bowl and toss with 1 tablespoon flour. Set aside.
Using a stand mixer fitted with paddle attachment, mix cake flour, sugar, baking powder and salt on the lowest speed until combined, about 20 seconds. With the mixer still running at the lowest speed, add 1 piece of butter at a time and continue to beat until all the butter is added. Increase speed to medium and continue to beat until the mixture resembles coarse meal, with butter bits no larger than small peas.
With the mixer running on low, add approximately half of the egg mixture to the flour mixture. Increase speed to medium-high and beat until light and fluffy, approximately 60 seconds. Reduce speed to medium-low and add remaining egg mixture and beat until incorporated, about 30 seconds (batter may look slightly curdled.) DO NOT OVERMIX. Add blueberries and lemon zest and gently fold into batter, taking care not to overmix.
Divide batter equally between the cake pans, smooth with a spatula and drop a few times on the counter to get rid of air bubbles. Bake at 350 degrees F for 20-25 minutes or until a toothpick inserted in the center of the cakes comes out with a few moist crumbs, rotating pans halfway through baking.
Cool the cakes in pans for 10 minutes then remove cakes to a wire rack and let cool completely before cutting. While the cakes are cooling make Lemon Curd (recipe below).